icydb-core 0.76.2

//! Module: db::session::sql::dispatch
//! Responsibility: session-owned SQL dispatch entrypoints that bind lowered SQL
//! commands onto structural planning, execution, and outward result shaping.
//! Does not own: SQL parsing or executor runtime internals.
//! Boundary: centralizes authority-aware SQL dispatch classification and result packaging.

mod computed;
mod lowered;

use crate::{
    db::{
        DbSession, MissingRowPolicy, PersistedRow, Query, QueryError,
        executor::{
            EntityAuthority, execute_sql_projection_rows_for_canister,
            execute_sql_projection_text_rows_for_canister,
        },
        identifiers_tail_match,
        query::{intent::StructuralQuery, plan::AccessPlannedQuery},
        session::sql::{
            SqlDispatchResult, SqlParsedStatement, SqlStatementRoute,
            aggregate::parsed_requires_dedicated_sql_aggregate_lane,
            computed_projection,
            projection::{
                SqlProjectionPayload, projection_labels_from_fields,
                projection_labels_from_projection_spec, sql_projection_rows_from_kernel_rows,
            },
        },
        sql::lowering::{
            LoweredBaseQueryShape, LoweredSelectShape, LoweredSqlQuery, bind_lowered_sql_query,
        },
        sql::parser::{
            SqlAggregateCall, SqlAggregateKind, SqlProjection, SqlSelectItem, SqlStatement,
            SqlTextFunction,
        },
    },
    traits::{CanisterKind, EntityKind, EntityValue},
};

#[cfg(feature = "perf-attribution")]
pub use lowered::LoweredSqlDispatchExecutorAttribution;

///
/// GeneratedSqlDispatchAttempt
///
/// Hidden generated-query dispatch envelope used by the facade helper to keep
/// generated route ownership in core while preserving the public EXPLAIN error
/// rewrite contract at the outer boundary.
///

#[doc(hidden)]
pub struct GeneratedSqlDispatchAttempt {
    entity_name: &'static str,
    explain_order_field: Option<&'static str>,
    result: Result<SqlDispatchResult, QueryError>,
}

impl GeneratedSqlDispatchAttempt {
    // Build one generated-query dispatch attempt with optional explain-hint context.
    const fn new(
        entity_name: &'static str,
        explain_order_field: Option<&'static str>,
        result: Result<SqlDispatchResult, QueryError>,
    ) -> Self {
        Self {
            entity_name,
            explain_order_field,
            result,
        }
    }

    /// Borrow the resolved entity name for this generated-query attempt.
    #[must_use]
    pub const fn entity_name(&self) -> &'static str {
        self.entity_name
    }

    /// Borrow the suggested deterministic order field for EXPLAIN rewrites.
    #[must_use]
    pub const fn explain_order_field(&self) -> Option<&'static str> {
        self.explain_order_field
    }

    /// Consume and return the generated-query dispatch result.
    pub fn into_result(self) -> Result<SqlDispatchResult, QueryError> {
        self.result
    }
}

#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub(in crate::db::session::sql) enum SqlGroupingSurface {
    Scalar,
    Grouped,
}

const fn unsupported_sql_grouping_message(surface: SqlGroupingSurface) -> &'static str {
    match surface {
        SqlGroupingSurface::Scalar => {
            "execute_sql rejects grouped SELECT; use execute_sql_grouped(...)"
        }
        SqlGroupingSurface::Grouped => "execute_sql_grouped requires grouped SQL query intent",
    }
}

// Enforce the generated canister query contract that empty SQL is unsupported
// before any parser/lowering work occurs.
fn trim_generated_query_sql_input(sql: &str) -> Result<&str, QueryError> {
    let sql_trimmed = sql.trim();
    if sql_trimmed.is_empty() {
        return Err(QueryError::unsupported_query(
            "query endpoint requires a non-empty SQL string",
        ));
    }

    Ok(sql_trimmed)
}

// Render the generated-surface entity list from the descriptor table instead
// of assuming every session-visible entity belongs on the public query export.
fn generated_sql_entities(authorities: &[EntityAuthority]) -> Vec<String> {
    let mut entities = Vec::with_capacity(authorities.len());

    for authority in authorities {
        entities.push(authority.model().name().to_string());
    }

    entities
}

// Project parsed SELECT items into one stable outward column contract while
// allowing parser-owned aliases to override only the final session label.
fn sql_projection_labels_from_select_statement(
    statement: &SqlStatement,
) -> Result<Option<Vec<String>>, QueryError> {
    let SqlStatement::Select(select) = statement else {
        return Err(QueryError::invariant(
            "SQL projection labels require SELECT statement shape",
        ));
    };
    let SqlProjection::Items(items) = &select.projection else {
        return Ok(None);
    };

    Ok(Some(
        items
            .iter()
            .enumerate()
            .map(|(index, item)| {
                select
                    .projection_alias(index)
                    .map_or_else(|| grouped_sql_projection_item_label(item), str::to_string)
            })
            .collect(),
    ))
}

// Render one grouped SELECT item into the public grouped-column label used by
// unified dispatch results.
fn grouped_sql_projection_item_label(item: &SqlSelectItem) -> String {
    match item {
        SqlSelectItem::Field(field) => field.clone(),
        SqlSelectItem::Aggregate(aggregate) => grouped_sql_aggregate_call_label(aggregate),
        SqlSelectItem::TextFunction(call) => {
            format!(
                "{}({})",
                grouped_sql_text_function_name(call.function),
                call.field
            )
        }
    }
}

// Keep the dedicated SQL aggregate lane on parser-owned outward labels
// without reopening alias semantics in lowering or runtime strategy state.
fn sql_aggregate_dispatch_label_override(statement: &SqlStatement) -> Option<String> {
    let SqlStatement::Select(select) = statement else {
        return None;
    };

    select.projection_alias(0).map(str::to_string)
}

// Render one aggregate call into one canonical SQL-style label.
fn grouped_sql_aggregate_call_label(aggregate: &SqlAggregateCall) -> String {
    let kind = match aggregate.kind {
        SqlAggregateKind::Count => "COUNT",
        SqlAggregateKind::Sum => "SUM",
        SqlAggregateKind::Avg => "AVG",
        SqlAggregateKind::Min => "MIN",
        SqlAggregateKind::Max => "MAX",
    };

    match aggregate.field.as_deref() {
        Some(field) => format!("{kind}({field})"),
        None => format!("{kind}(*)"),
    }
}

// Render one reduced SQL text-function identifier into one stable uppercase
// SQL label for outward column metadata.
const fn grouped_sql_text_function_name(function: SqlTextFunction) -> &'static str {
    match function {
        SqlTextFunction::Trim => "TRIM",
        SqlTextFunction::Ltrim => "LTRIM",
        SqlTextFunction::Rtrim => "RTRIM",
        SqlTextFunction::Lower => "LOWER",
        SqlTextFunction::Upper => "UPPER",
        SqlTextFunction::Length => "LENGTH",
        SqlTextFunction::Left => "LEFT",
        SqlTextFunction::Right => "RIGHT",
        SqlTextFunction::StartsWith => "STARTS_WITH",
        SqlTextFunction::EndsWith => "ENDS_WITH",
        SqlTextFunction::Contains => "CONTAINS",
        SqlTextFunction::Position => "POSITION",
        SqlTextFunction::Replace => "REPLACE",
        SqlTextFunction::Substring => "SUBSTRING",
    }
}

// Resolve one generated query route onto the descriptor-owned authority table.
fn authority_for_generated_sql_route(
    route: &SqlStatementRoute,
    authorities: &[EntityAuthority],
) -> Result<EntityAuthority, QueryError> {
    let sql_entity = route.entity();

    for authority in authorities {
        if identifiers_tail_match(sql_entity, authority.model().name()) {
            return Ok(*authority);
        }
    }

    Err(unsupported_generated_sql_entity_error(
        sql_entity,
        authorities,
    ))
}

// Keep the generated query-surface unsupported-entity contract stable while
// moving authority lookup out of the build-generated shim.
fn unsupported_generated_sql_entity_error(
    entity_name: &str,
    authorities: &[EntityAuthority],
) -> QueryError {
    let mut supported = String::new();

    for (index, authority) in authorities.iter().enumerate() {
        if index != 0 {
            supported.push_str(", ");
        }

        supported.push_str(authority.model().name());
    }

    QueryError::unsupported_query(format!(
        "query endpoint does not support entity '{entity_name}'; supported: {supported}"
    ))
}

impl<C: CanisterKind> DbSession<C> {
    // Build the shared structural SQL projection execution inputs once so
    // value-row and rendered-row dispatch surfaces only differ in final packaging.
    fn prepare_structural_sql_projection_execution(
        &self,
        query: StructuralQuery,
        authority: EntityAuthority,
    ) -> Result<(Vec<String>, AccessPlannedQuery), QueryError> {
        // Phase 1: build the structural access plan once and freeze its outward
        // column contract for all projection materialization surfaces.
        let (_, plan) =
            self.build_structural_plan_with_visible_indexes_for_authority(query, authority)?;
        let projection = plan.projection_spec(authority.model());
        let columns = projection_labels_from_projection_spec(&projection);

        Ok((columns, plan))
    }

    // Execute one structural SQL load query and return only row-oriented SQL
    // projection values, keeping typed projection rows out of the shared SQL
    // query-lane path.
    pub(in crate::db::session::sql) fn execute_structural_sql_projection(
        &self,
        query: StructuralQuery,
        authority: EntityAuthority,
    ) -> Result<SqlProjectionPayload, QueryError> {
        // Phase 1: build the shared structural plan and outward column contract once.
        let (columns, plan) = self.prepare_structural_sql_projection_execution(query, authority)?;

        // Phase 2: execute the shared structural load path with the already
        // derived projection semantics.
        let projected =
            execute_sql_projection_rows_for_canister(&self.db, self.debug, authority, plan)
                .map_err(QueryError::execute)?;
        let (rows, row_count) = projected.into_parts();

        Ok(SqlProjectionPayload::new(columns, rows, row_count))
    }

    // Execute one structural SQL load query and return render-ready text rows
    // for the dispatch lane when the terminal short path can prove them
    // directly.
    fn execute_structural_sql_projection_text(
        &self,
        query: StructuralQuery,
        authority: EntityAuthority,
    ) -> Result<SqlDispatchResult, QueryError> {
        // Phase 1: build the shared structural plan and outward column contract once.
        let (columns, plan) = self.prepare_structural_sql_projection_execution(query, authority)?;

        // Phase 2: execute the shared structural load path with the already
        // derived projection semantics while preferring rendered SQL rows.
        let projected =
            execute_sql_projection_text_rows_for_canister(&self.db, self.debug, authority, plan)
                .map_err(QueryError::execute)?;
        let (rows, row_count) = projected.into_parts();

        Ok(SqlDispatchResult::ProjectionText {
            columns,
            rows,
            row_count,
        })
    }

    // Execute one typed SQL delete query while keeping the row payload on the
    // typed delete executor boundary that still owns non-runtime-hook delete
    // commit-window application.
    fn execute_typed_sql_delete<E>(&self, query: &Query<E>) -> Result<SqlDispatchResult, QueryError>
    where
        E: PersistedRow<Canister = C> + EntityValue,
    {
        let plan = self
            .compile_query_with_visible_indexes(query)?
            .into_prepared_execution_plan();
        let deleted = self
            .with_metrics(|| self.delete_executor::<E>().execute_sql_projection(plan))
            .map_err(QueryError::execute)?;
        let (rows, row_count) = deleted.into_parts();
        let rows = sql_projection_rows_from_kernel_rows(rows).map_err(QueryError::execute)?;

        Ok(SqlProjectionPayload::new(
            projection_labels_from_fields(E::MODEL.fields()),
            rows,
            row_count,
        )
        .into_dispatch_result())
    }

    // Lower one parsed SQL query/explain route once for one resolved authority
    // and preserve grouped-column metadata for grouped SELECT dispatch.
    fn lowered_sql_query_dispatch_inputs_for_authority(
        parsed: &SqlParsedStatement,
        authority: EntityAuthority,
        unsupported_message: &'static str,
    ) -> Result<(LoweredSqlQuery, Option<Vec<String>>), QueryError> {
        let lowered = parsed.lower_query_lane_for_entity(
            authority.model().name(),
            authority.model().primary_key.name,
        )?;
        let projection_columns = matches!(lowered.query(), Some(LoweredSqlQuery::Select(_)))
            .then(|| sql_projection_labels_from_select_statement(&parsed.statement))
            .transpose()?;
        let query = lowered
            .into_query()
            .ok_or_else(|| QueryError::unsupported_query(unsupported_message))?;

        Ok((query, projection_columns.flatten()))
    }

    // Execute one parsed SQL query route through the shared aggregate,
    // computed-projection, and lowered query lane so typed and generated
    // dispatch only differ at the final SELECT/DELETE packaging boundary.
    fn dispatch_sql_query_route_for_authority(
        &self,
        parsed: &SqlParsedStatement,
        authority: EntityAuthority,
        unsupported_message: &'static str,
        dispatch_select: impl FnOnce(
            &Self,
            LoweredSelectShape,
            EntityAuthority,
            bool,
            Option<Vec<String>>,
        ) -> Result<SqlDispatchResult, QueryError>,
        dispatch_delete: impl FnOnce(
            &Self,
            LoweredBaseQueryShape,
            EntityAuthority,
        ) -> Result<SqlDispatchResult, QueryError>,
    ) -> Result<SqlDispatchResult, QueryError> {
        // Phase 1: keep aggregate and computed projection classification on the
        // shared parsed route so both dispatch surfaces honor the same lane split.
        if parsed_requires_dedicated_sql_aggregate_lane(parsed) {
            let command =
                Self::compile_sql_aggregate_command_core_for_authority(parsed, authority)?;

            return self.execute_sql_aggregate_dispatch_for_authority(
                command,
                authority,
                sql_aggregate_dispatch_label_override(&parsed.statement),
            );
        }

        if let Some(plan) = computed_projection::computed_sql_projection_plan(&parsed.statement)? {
            return self.execute_computed_sql_projection_dispatch_for_authority(plan, authority);
        }

        // Phase 2: lower the remaining query route once, then let the caller
        // decide only the final outward result packaging.
        let (query, projection_columns) = Self::lowered_sql_query_dispatch_inputs_for_authority(
            parsed,
            authority,
            unsupported_message,
        )?;
        let grouped_surface = query.has_grouping();

        match query {
            LoweredSqlQuery::Select(select) => {
                dispatch_select(self, select, authority, grouped_surface, projection_columns)
            }
            LoweredSqlQuery::Delete(delete) => dispatch_delete(self, delete, authority),
        }
    }

    // Execute one parsed SQL EXPLAIN route through the shared computed-
    // projection and lowered explain lanes so typed and generated dispatch do
    // not duplicate the same explain classification tree.
    fn dispatch_sql_explain_route_for_authority(
        &self,
        parsed: &SqlParsedStatement,
        authority: EntityAuthority,
    ) -> Result<SqlDispatchResult, QueryError> {
        // Phase 1: keep computed-projection explain ownership on the same
        // parsed route boundary as the shared query lane.
        if let Some((mode, plan)) =
            computed_projection::computed_sql_projection_explain_plan(&parsed.statement)?
        {
            return self
                .explain_computed_sql_projection_dispatch_for_authority(mode, plan, authority)
                .map(SqlDispatchResult::Explain);
        }

        // Phase 2: lower once for execution/logical explain and preserve the
        // shared execution-first fallback policy across both callers.
        let lowered = parsed.lower_query_lane_for_entity(
            authority.model().name(),
            authority.model().primary_key.name,
        )?;
        if let Some(explain) =
            self.explain_lowered_sql_execution_for_authority(&lowered, authority)?
        {
            return Ok(SqlDispatchResult::Explain(explain));
        }

        self.explain_lowered_sql_for_authority(&lowered, authority)
            .map(SqlDispatchResult::Explain)
    }

    // Validate that one SQL-derived query intent matches the grouped/scalar
    // execution surface that is about to consume it.
    pub(in crate::db::session::sql) fn ensure_sql_query_grouping<E>(
        query: &Query<E>,
        surface: SqlGroupingSurface,
    ) -> Result<(), QueryError>
    where
        E: EntityKind,
    {
        match (surface, query.has_grouping()) {
            (SqlGroupingSurface::Scalar, false) | (SqlGroupingSurface::Grouped, true) => Ok(()),
            (SqlGroupingSurface::Scalar, true) | (SqlGroupingSurface::Grouped, false) => Err(
                QueryError::unsupported_query(unsupported_sql_grouping_message(surface)),
            ),
        }
    }

    /// Execute one reduced SQL statement into one unified SQL dispatch payload.
    pub fn execute_sql_dispatch<E>(&self, sql: &str) -> Result<SqlDispatchResult, QueryError>
    where
        E: PersistedRow<Canister = C> + EntityValue,
    {
        let parsed = self.parse_sql_statement(sql)?;

        self.execute_sql_dispatch_parsed::<E>(&parsed)
    }

    /// Execute one parsed reduced SQL statement into one unified SQL payload.
    pub fn execute_sql_dispatch_parsed<E>(
        &self,
        parsed: &SqlParsedStatement,
    ) -> Result<SqlDispatchResult, QueryError>
    where
        E: PersistedRow<Canister = C> + EntityValue,
    {
        match parsed.route() {
            SqlStatementRoute::Query { .. } => self.dispatch_sql_query_route_for_authority(
                parsed,
                EntityAuthority::for_type::<E>(),
                "execute_sql_dispatch accepts SELECT or DELETE only",
                |session, select, authority, grouped_surface, projection_columns| {
                    if grouped_surface {
                        let columns = projection_columns.ok_or_else(|| {
                            QueryError::unsupported_query(
                                "grouped SQL dispatch requires explicit grouped projection items",
                            )
                        })?;

                        return session.execute_lowered_sql_grouped_dispatch_select_core(
                            select, authority, columns,
                        );
                    }

                    let payload = session.execute_lowered_sql_projection_core(select, authority)?;
                    if let Some(columns) = projection_columns {
                        let (_, rows, row_count) = payload.into_parts();

                        return Ok(SqlProjectionPayload::new(columns, rows, row_count)
                            .into_dispatch_result());
                    }

                    Ok(payload.into_dispatch_result())
                },
                |session, delete, _authority| {
                    let typed_query = bind_lowered_sql_query::<E>(
                        LoweredSqlQuery::Delete(delete),
                        MissingRowPolicy::Ignore,
                    )
                    .map_err(QueryError::from_sql_lowering_error)?;

                    session.execute_typed_sql_delete(&typed_query)
                },
            ),
            SqlStatementRoute::Explain { .. } => self
                .dispatch_sql_explain_route_for_authority(parsed, EntityAuthority::for_type::<E>()),
            SqlStatementRoute::Describe { .. } => {
                Ok(SqlDispatchResult::Describe(self.describe_entity::<E>()))
            }
            SqlStatementRoute::ShowIndexes { .. } => {
                Ok(SqlDispatchResult::ShowIndexes(self.show_indexes::<E>()))
            }
            SqlStatementRoute::ShowColumns { .. } => {
                Ok(SqlDispatchResult::ShowColumns(self.show_columns::<E>()))
            }
            SqlStatementRoute::ShowEntities => {
                Ok(SqlDispatchResult::ShowEntities(self.show_entities()))
            }
        }
    }

    /// Execute one parsed reduced SQL statement through the generated canister
    /// query/explain surface for one already-resolved dynamic authority.
    ///
    /// This keeps the canister SQL facade on the same reduced SQL ownership
    /// boundary as typed dispatch without forcing the outer facade to reopen
    /// typed-generic routing just to preserve parity for computed projections.
    #[doc(hidden)]
    pub fn execute_generated_query_surface_dispatch_for_authority(
        &self,
        parsed: &SqlParsedStatement,
        authority: EntityAuthority,
    ) -> Result<SqlDispatchResult, QueryError> {
        match parsed.route() {
            SqlStatementRoute::Query { .. } => self.dispatch_sql_query_route_for_authority(
                parsed,
                authority,
                "generated SQL query surface requires query or EXPLAIN statement lanes",
                |session, select, authority, grouped_surface, projection_columns| {
                    if grouped_surface {
                        let columns = projection_columns.ok_or_else(|| {
                            QueryError::unsupported_query(
                                "grouped SQL dispatch requires explicit grouped projection items",
                            )
                        })?;

                        return session
                            .execute_lowered_sql_grouped_dispatch_select_core(select, authority, columns);
                    }

                    let result =
                        session.execute_lowered_sql_dispatch_select_text_core(select, authority)?;
                    if let Some(columns) = projection_columns {
                        let SqlDispatchResult::ProjectionText {
                            rows, row_count, ..
                        } = result
                        else {
                            return Err(QueryError::invariant(
                                "generated scalar SQL dispatch text path must emit projection text rows",
                            ));
                        };

                        return Ok(SqlDispatchResult::ProjectionText {
                            columns,
                            rows,
                            row_count,
                        });
                    }

                    Ok(result)
                },
                |session, delete, authority| {
                    session.execute_lowered_sql_dispatch_delete_core(&delete, authority)
                },
            ),
            SqlStatementRoute::Explain { .. } => {
                self.dispatch_sql_explain_route_for_authority(parsed, authority)
            }
            SqlStatementRoute::Describe { .. }
            | SqlStatementRoute::ShowIndexes { .. }
            | SqlStatementRoute::ShowColumns { .. }
            | SqlStatementRoute::ShowEntities => Err(QueryError::unsupported_query(
                "generated SQL query surface requires query or EXPLAIN statement lanes",
            )),
        }
    }

    /// Execute one raw SQL string through the generated canister query surface.
    ///
    /// This hidden helper keeps parse, route, authority, and metadata/query
    /// dispatch ownership in core so the build-generated `sql_dispatch` shim
    /// stays close to a pure descriptor table plus public ABI wrapper.
    #[doc(hidden)]
    #[must_use]
    pub fn execute_generated_query_surface_sql(
        &self,
        sql: &str,
        authorities: &[EntityAuthority],
    ) -> GeneratedSqlDispatchAttempt {
        // Phase 1: normalize and parse once so every generated route family
        // shares the same SQL ownership boundary.
        let sql_trimmed = match trim_generated_query_sql_input(sql) {
            Ok(sql_trimmed) => sql_trimmed,
            Err(err) => return GeneratedSqlDispatchAttempt::new("", None, Err(err)),
        };
        let parsed = match self.parse_sql_statement(sql_trimmed) {
            Ok(parsed) => parsed,
            Err(err) => return GeneratedSqlDispatchAttempt::new("", None, Err(err)),
        };

        // Phase 2: keep SHOW ENTITIES descriptor-owned and resolve all other
        // generated routes against the emitted authority table exactly once.
        if matches!(parsed.route(), SqlStatementRoute::ShowEntities) {
            return GeneratedSqlDispatchAttempt::new(
                "",
                None,
                Ok(SqlDispatchResult::ShowEntities(generated_sql_entities(
                    authorities,
                ))),
            );
        }
        let authority = match authority_for_generated_sql_route(parsed.route(), authorities) {
            Ok(authority) => authority,
            Err(err) => return GeneratedSqlDispatchAttempt::new("", None, Err(err)),
        };

        // Phase 3: dispatch the resolved route through the existing query,
        // explain, and metadata helpers without rebuilding route ownership in
        // the generated build output.
        let entity_name = authority.model().name();
        let explain_order_field = parsed
            .route()
            .is_explain()
            .then_some(authority.model().primary_key.name);
        let result = match parsed.route() {
            SqlStatementRoute::Query { .. } | SqlStatementRoute::Explain { .. } => {
                self.execute_generated_query_surface_dispatch_for_authority(&parsed, authority)
            }
            SqlStatementRoute::Describe { .. } => Ok(SqlDispatchResult::Describe(
                self.describe_entity_model(authority.model()),
            )),
            SqlStatementRoute::ShowIndexes { .. } => Ok(SqlDispatchResult::ShowIndexes(
                self.show_indexes_for_store_model(authority.store_path(), authority.model()),
            )),
            SqlStatementRoute::ShowColumns { .. } => Ok(SqlDispatchResult::ShowColumns(
                self.show_columns_for_model(authority.model()),
            )),
            SqlStatementRoute::ShowEntities => unreachable!(
                "SHOW ENTITIES is handled before authority resolution for generated query dispatch"
            ),
        };

        GeneratedSqlDispatchAttempt::new(entity_name, explain_order_field, result)
    }
}